The present invention relates to an elevator. In particular, but not exclusively, the present invention relates to a single joint elevator for supporting tubular members for use in downhole operations.
Presently known single joint elevators are used for raising lengths of drill pipe, borehole casing or production tubing from a pipe stand rack in a derrick, or a pipe storage area on the main deck of an onshore or offshore oil rig, or from a xe2x80x9cmouse holexe2x80x9d in the drilling floor, and for locating the drill pipe (or the borehole casing or production tubing) at the upper end of a drill pipe string protruding through a kelly in the drill floor. The single joint elevator is typically suspended from a hoist wire or winch mounted on the derrick. In addition to their use in making up drill string, single joint elevators are also utilised when xe2x80x9ctripping outxe2x80x9d, that is retrieving a drill string from a borehole. Typically, when removed from the drill string, each section or stand of drill pipe is pushed out of a Vee door on to a catwalk adjacent to the pipe storage area via a pipe discharge ramp, for subsequent pick up by a crane. Such ramps comprise an inclined surface upon which the drill pie is laid, using the single joint elevator, and subsequently released, discharging from the ramp below drill floor deck level.
The structure of existing single joint elevators is such that the elevators often include sharp, angular, or protruding profiles which may catch on the upper end of the ramp. This may result in the single joint elevator carrying the drill pipe section fouling on the ramp, or xe2x80x9cbouncingxe2x80x9d from the ramp when the elevator becomes unstuck, creating a potential hazard to operators present or. the drilling floor. Also, the single joint elevators include latches and securing mechanisms for locking the elevator to the pipe section. Due to the structure of single joint elevators, the orientation of the clamp with respect to the pipe ramp is not predetermined and, consequently, it has been known for the clamp to unlock by fouling on the pipe ramp, causing the pipe section to be released prematurely.
It is amongst the objects of the present invention to is obviate or mitigate at least one of the foregoing disadvantages.
Accordingly, the present invention provides an elevator for supporting an elongate member, the elevator comprising a housing having retaining means for retaining the elongate member, and an Inclined outer surface.
References herein and in the following description to elevators are generally to single joint elevators. However, as will be understood by persons skilled in the art, the present invention is not limited to single joint elevators, and applies equally to other types of elevators. Furthermore, references herein and in the following description to a drill pipe, or to a section or stand of drill pipe, are to drill pipes, borehole casings and/or production tubing, or to a section or stand of such drill pipes, borehole casing and/or production tubing.
Thus the present invention may provide an elevator having an inclined outer surface which may prevent the elevator from becoming caught upon a fee door, discharge ramp, or any projecting or angular surface for discharging the elongate member.
The elongate member may be a tubular member such as a section or stand of drill pope. The pipe may be for use in downhole oilfield operations. Conveniently, the elevator may be for supporting the pipe during xe2x80x9ctripping outxe2x80x9d or removal thereof from a borehole and/or during removal thereof from a mouse hole adjacent to the borehole. The elevator may also be for supporting the pipe during run-in thereof into the borehole.
Preferably, the housing comprises a ring defining a throughbore. The ring may comprise two sections which together form the ring, and a hinge coupling the two sections together, for allowing the ring to open and close. The hinge may be a single or double hinge. The ring may be generally elliptical, oval, or circular in plan view and may include lifting eyes, as will be discussed in more detail below, or alternative projections For lifting or other uses. The ring may further comprise an outer wall forming a boundary of the ring, an upper plate extending radially inwardly from the outer wall and defining an upper opening, and a lower plate extending radially inwardly and defining a lower opening. The retaining means may comprise an inner wall of the ring, defining an abuttment surface for abutting the elongate member. The upper opening of the ring may be inclined or square in cross-section to suit differing profiles of drill pipe, borehole casing and/or production tubing. The upper opening may define the abuttment surface. The inclined abuttment surface of the upper opening may be adapted to abut a collar of a section of drill pipe.
Preferably the upper and lower openings are circular in cross-section, and offset from the longitudinal axis of the housing. Thus the present invention may allow the elevator, when supporting the elongate member, to be disposed inclined from the vertical to facilitate discharge of the elongate member on the discharge ramp.
Preferably the inclined outer surface of the elevator is provided on a lower portion thereof. The outer surface may be of a metal or an elastomeric material. The lower portion of the elevator may comprise a truncated cone, projecting downwardly from the housing, and tapering from the housing to an opening. The opening of the cone may define an abuttment surface for abutting or guiding the elongate member.
Alternatively, the inclined outer surface of the elevator may be formed peripherally on the elevator. An outer wall of the housing may comprise the inclined outer surface of the elevator.
In a further alternative, the inclined surface may comprise an inclined plate, wedge or the like, projecting downwardly from the housing, or formed peripherally on the elevator.
Preferably, the elevator further comprises locking means for releasably locking the housing to retain an elongate member therein. Thus the present invention may allow the housing to be locked to securely support the elongate member. The locking means may comprise a latch arm formed on a first half of the housing, and a catch formed on the second half of the housing. The latch arm may be spring loaded. The catch may include a spring loaded cover to releasably retain the latch arm to the catch.
Preferably, the elevator further comprises support means for supporting the housing. The support means may further comprise one or more lifting eyes provided on the housing for coupling to hoisting means. Preferably the hoisting means comprises wire rope slings and a swivel block. Alternatively, the hoisting means may comprise a cable, chain, link, arm or the like coupled to a crane, a lifting pulley and winch assembly, or the like. The lifting eyes may be disposed proximal to a lock side of the elevator. The elevator may further comprise an insert for coupling to the elongate member enabling the elevator to support elongate members of various cross-sectional dimensions. The insert may be tubular, for coupling to the pine. A number of inserts of various cross-sectional dimensions may be provided.